Alignment

[pshovest]

Originally Posted by isarkisov

Just checked my tires, looks like 40 PSI is the max pressure and there is "outside" marking.

Don't you think 40 PSI in front would be too much causing very harsh ride and hard on suspension?

Not at all. It all depends on how badly you want to avoid buying new tires.
I'm surprised your max inflation pressure is only 40 psi. What type of tires are these? My Goodyear LS2 runflats need 50psi to get the advertised load rating. My non-runflats on other Bimmers are in the mid 40's. I run fronts at 40 and rears at 36 on the X5. Outside edge wear has all but disappeared.

[isarkisov]

Originally Posted by pshovest

Not at all. It all depends on how badly you want to avoid buying new tires.
I'm surprised your max inflation pressure is only 40 psi. What type of tires are these? My Goodyear LS2 runflats need 50psi to get the advertised load rating. My non-runflats on other Bimmers are in the mid 40's. I run fronts at 40 and rears at 36 on the X5. Outside edge wear has all but disappeared.

I was wrong, when I looked at my tires this morning it says 50 psi max. Not sure where I got 40 psi

They are Pirelli SCORPION VERDE ALL SEASON RUN FLAT 255/50R19 107H XL. I just looked them up in Tirerack and here what it says:

"XL/RF tires required if 255/50-19 is used on rear axle. This requires higher tire pressure levels of 42psi for proper load."

I inflated to 40 psi all around this morning, should I go with 42 in the rear?

[ard]

Originally Posted by pshovest

My Goodyear LS2 runflats need 50psi to get the advertised load rating. .

SO there is a maximum load that is specified by BMW... and to achieve THIS load, you should inflate the tires to the max pressure ON THE DOORJAMB PLACARD.

This can be independent from the maximum load for a given tire, and the inflation pressure to achieve that load.

My recollection is that you do not need to run tires at 50, 51, whatever to hit your maximum load rating that BMW states the car can handle. (and presumably BMW has determined 'at a fully laden configuration, the rear axle sees XXX lbs and therefore needs YY psi'.) And both of these numbers are UNDER the max tire load rating and max PSI ratings

So two different things... Correct?

[pshovest]

Originally Posted by ard

SO there is a maximum load that is specified by BMW... and to achieve THIS load, you should inflate the tires to the max pressure ON THE DOORJAMB PLACARD.

This can be independent from the maximum load for a given tire, and the inflation pressure to achieve that load.

My recollection is that you do not need to run tires at 50, 51, whatever to hit your maximum load rating that BMW states the car can handle. (and presumably BMW has determined 'at a fully laden configuration, the rear axle sees XXX lbs and therefore needs YY psi'.) And both of these numbers are UNDER the max tire load rating and max PSI ratings

So two different things... Correct?

Yes, two different things.
I'd like to think that BMW did the calcs as you describe, but my gut tells me the lawyers were also involved to prevent oversteer. My point was that tire mfr's have a recommended pressure to achieve the tire's load rating and that BMW's pressures aren't even close to that limit. Virtually all of the 13 Bimmer's I've owned need 4-6 psi higher pressure than shown on the B pillar to get uniform front tire wear.